Method of producing spiral pipe



6 Sheets-Sheet 1 INVENTOR.

N .mwwi

June 11, 1963 1 J. BERKELEY METHOD oF PRoDucING SPIRAL PIPE Filed Feb.1o, 1958 URENC June 11, 1963 l.. J. BERKELEY METHOD oF PRonucING sPIRALPIPE 6 Sheets-Sheet 2 Filed Feb. l0, 1958 1 INVENTOR.

ATTORNEY URENCE J KELEY BY June 11, 1963 L. J. BERKELEY 3,093,103

METHOD OF PRODUCING SPIRAL PIPE Filed Feb.l 10, 1958 6 Sheets-Sheet 3 g/INVENToR.

/ RENCE J. BERKELEY ATTORNEY June 11, 1963 1 J. BERKELEY 3,093,103

METHOD OF PRODUCING SPIRAL PIPE Filed Feb. l0, 1958 6 Sheets-Sheet 4INVENTOR. AU RENCE J. BERKELEY BY QW June 11, 1963 L. J. BERKELEY3,093,103

METHOD OF' PRODUCING SPIRAL. PIPE Filed Feb. 10, 1958 v 6 Sheets-Sheet 5l q E l l a2 53 1 Q N INVENTOR. LAURENCE J. BERKELEY ATTORNE June 11,1963 L. J. BERKELEY 3,093,103

METHOD OF PRODUCING SPIRAI.. PIPE Filed Feb. 10, 1958 6 Sheets-Sheet 6 SE l m N Q. 2 m u -1 IN VEN TOR.

ATTORNEY E L RENCE J. BERKELEY l ML BY n United States My inventionlrelates to a method of producing pipe which is formed by helicallywinding an elongated strip of `metal into a series of relatedconvolutions which `are welded to each other at the edges of theconvolutions. Pipe so produced is commonly called spiral pipe, orspirally formed pipe.

One feature of my invention is that spiral pipe produced by my methodis, at any point, not only within the normal commercial requirements ofaccuracy and ovality, but also within the most stringent requirements insuch respects for certain applications of the Ordnance Department of theUnited States.

Another feature of my invention is that with the use of my method, thestrip is curled to a diameter slightly larger than the desired diameterof the spiral pipe being produced, and such slightly larger diametercurled strip is confined in a cage of elongated rolls, the effect-ivediameter of the cage being that of the desired diameter of the pipebeing produced. Such difference in diameters effects a certain amount ofcold working of steel strip, and no special devices or equipment arerequired to keep the edges even in up and down direction. Suchdifference -in diameters assures both roundness of the pipe and that itis of the desired diameter. Although such difference in diametersinduces no circumferential resistance to the movement of the curledstrip in the cage of rolls Ias would tend to unwind or open the seam,said rolls do exert a longitudinal resistance which tends to assureabutment of the edges for welding.

Another feature of my invention is that the camber commerciallyallowable in steel strip, as received from the rolling mills, isabsorbed during the production of spiral pipe with the use of my-improved method.

As received from the rolling mills, steel strip or sheet, of thecharacter used in the manufacture of spirally formed pipe, has a slightlateral carnber which ordinarily would intenfere with the properregistry of the edges of the sheet when wound helically into tubular orpip-e form. Any flat metal piece produced by rolling is characterized bycamber, and this camber is not uniform; it may not be compensating; andgenerally is unpredictable. Camber of 1A per 8 of length is allowable insteel strip as sold commercially by rolling mills.

With the use of previously known methods and apparatus, when suchcambered flat steel strip is wound helically in the absence of specialdevices Aor equipment, the pipe which is produced either will not be ofuniform diameter or it will have imperfect welds. Both of these resultsrender the pipe unsalable commercially. Many attempts have been made toovercome the diculties mentioned above with the use of various devicesand equipment, and none have been completely satisfactory.

Another feature of my invention is that the welded joint of steel pipeproduced by my method is free from leaks and is capable of withstandinghigh pressures without rupture, or bursting. Tests made by the OrdnanceDepartment of the United States of spirally formed and welded steel pipemade with my method and apparatus have established that the bursting, orrupture, point of such pipe is that of the parent metal, and never atthe weld. Such tests were made even with pipe produced from #4130 steelstrip. Heretofore it had been believed to be impossible tosatisfactorily form and weld spiral pipe from #4130 steel strip becauseof the inherent spring back characteristics of such a steel.

. ate A t l"ice 3,693,103l Patented June 11, 1963 Another lfeature of myinvention is that with the use of my method, spiral pipe may be producedfrom almost any of the various types iof carbon steels, or carbon alloysteels.

Another feature of my invention is that with the use of -my improvedmethod, spirally formed and welded pipe in a very wide range ofdiameters may be produced continuously from a wide range of widths andthicknesses of metal strip.

Referring to said drawings:

FIG. 1 is a perspective View showing generally a form of spiral pipeforming and welding apparatus embodying my invention; a metal strip anda roller leveler; means for feeding uncoiled strip to the apparatus;etc.

FIG. 2 is a front side elevation of a spiral pipe forming and weldingapparatus as indicated in FIG. l.

FIG. 3 is a top plan view of the spiral pipe forming and weldingapparatus, roller leveler, strip yfeeding means, indicated in FIGS. 2and l.

FIG. 4 is an enlarged fragmentary (front side elevation Cthezleft-handend po-rt-ion of the apparatus shown in IFIG. 5 is a somewhatdiagrammatic front end elevation of the structures shown in FIG. 1.

FIG. 6 is an enlarged fragmentary front end elevation of the apparatusshown in FIG. 2.

FIG. 7 is an enlarged left-hand end View of a slatted form of center, ormandrel, roll.

FIG. 8 is a sectional view of the structure `shown in FIG. 7, taken onthe line 3-8 in FIG. 7.

FIG. 9 is an enlarged front end elevation, pantly in section, of aslatted form of center, or mandrel, roll.

FIG. l0 is a tfragmentary sectional View of the structure shown in FIG.9, taken on the line 10-10 in FIG. 9.

FIG. 1l is an enlarged View of the air cylinder valve assembly to whichthe air cylinders for a slatted roll are connected.

In the production of a wide range of diameter sizes of spiral pipe fromvarious types of steel strip of wide ranges of width and thicknesseswith the use of my improved method and apparatus, all of the outerrol-ls and the center roll, or mandrel roll, of the cage of rolls of theapparatus may be of a solid roll construction, i.e. an ordinary rollhaving a solid outer surface.

In the production of spiral pipe of some diameters and wall thicknesses,it may ybe more desirable to have the center roll, or mandrel roll, and/or one or more or all of the outer rolls which form the cage of rolls ofa slatted construction in order `to Ifacilitate the movement of thestrip as it is wound helically by the apparatus. What I term a slattedform of roll, is a cylindrical roll comprised of segments, each segmentindependently being capable of movement axially for a predetermineddistance toward the ffront end of the apparatus along with the pipebein-g formed. As a segment of such a roll rotates out of contact withthe workpiece, that segment of the roll is returned automatically to itsinitial position, or towards the rearward end of the apparatus shown inthe drawings.

The essential features. of my improved method of and apparatus forproducing spiral pipe are ythe same whether the rolls be of solid form,or of slatted form, or comb-inations of both forms.

Although in the drawings only the center roll, or mandrel roll, is shownas a driven roll, it is to be understood that any or all of the outerrolls may be driven in a similar manner, i-f desired.

4Referring to the drawings; the spiral pipe forming and weldingapparatus, indicated generally by the reference mark 1, is mounted on ahorizontal bed plate, or base, 2 which has rigidly secured thereto avertical supporting column member 3. The column member 3 is provided,

3 conveniently, with four spaced-apart horizontal guideways, which areindicated at 4, 5, 6, and 7 in FIGS. 1 and 2. Each of said guideways `4,5, 6, and 7 has a T-shaped slot in which Tahead screwathreaded studs areslidably mounted for rigidly securing roll support members to the columnmember 3, as hereinafter described.

As best shown in FIG. 6, a series of outer rolls which form a roll cageincludes a lower rear roll 12, an upper rear roll 13, an upper frontroll 14, a lower front roll 15, and a bottom roll 16, which arejournalled at their front ends in respective ybearings 12a, 13a, 14a,15a, and 16a. The bearings 12a, 13a, 14a, 15a, and 16a are formed atlthe inner ends of their respective shafts 22, 23, 24, 25, and 26. Therolls 12, 13, 14, 15, and 16 are jcurnalled at their rear ends inrespective bearings 12b, 13b, 14h, 15b, and 1Gb, formed at the innerends of their respective shafts 27, 28, 2.9, 30, and 31.

The bearing shaft 22 is slidably mounted in a guide bearing in the rollsupport member l35; the bearing shaft 23 is slidably mounted in a guidebearing in the roll support member 36; the bearing shaft 24 is slidablymounted in a guide bearing in the roll support member 37; the bearingshaft 25 is slidably mounted in a guide bearing in the roll supportmember 38; and the bearing shaft 26 is slidably mounted in a guidebearing in the roll support member 39.

The `bearing shaft 27 is slidably mounted in a guide bearing in the rollsupporting member 45; the bearing shaft 28 is slidably mounted in aguide bearing in the roll support member 46; the bearing shaft 29 isslidably mounted in a guide bearing in the roll support member 47; thebearing shaft '30 is slidably mounted in a guide bearing in the rollsupport member 48; and the bearing shaft 31 is slidably mounted in aguide bearing in the roll suppont member 49.

As the spiral pipe apparatus is adaptable for producing spiral pipe fromstrip or varying widths and pipe of different diameters within adetermined range, it is desirable that the front and rear roll supportsfor the rolls be movable as a unit to properly position the rolls wtihrespect to -the point of weld of the pipe 4being formed. Accordingly,the front and rear roll supports 35 'and 45 for the lower rear roll 12may be moved as a unit by means yof screw shafts S-50 cooperating withrespective rigid nut means in the roll supports 35 and `45. The shafts50-50 may be turned to effect simultaneous horizontal movement of bothroll supports 35 and 45, in the wellknown mechanical manner by means ofclutch, gear, etc. means operatively Vconnected to power drive means bya shaft and drive pulley, as indicated diagrammatieally at 52 in FIG. 2.

Correspondingly, the roll supports 36 and 46 of the roll 13; the rollsupports 37 and 47 of the roll 14; and vthe roll supports 38 and 48 ofthe roll 1S may be moved simultaneously in the same manner by respectivescrew shafts SLS-'54', 55-55, and 56-56" operatively connected in thesame manner to pulley and motor means, as indicated diagrammatically at58 in FIG. 2. The front roll support 39 and the rear roll support 49 forthe .bottom roll 16 may be moved simultaneously as a unit by means ofscrew shafts 60-60 operatively connected to the means indicateddiagrammatically at 52, as heretofore described.

The means to effect simultaneous movement of the roll supports at theopposite ends of the rolls forms no part of my present invention, asvarious such means for effecting the desired pulpose are old and wellknown, and require only ordinary designing skill of mechanicalmovements. Accordingly, I deem it not necessary to fully show anddescribe in detail any of the well-known various ararngements which maybe utilized to effect the desired purpose.

When any one of the rolls 12 to 15, inclusive, has been moved to thedesired position, the front and rear rolls supports for the roll arerigidly secured to the column member 3 by means of fthe T-headscrew-threaded studs roll support member for the shaft.

extending through suitable openings in the roll support, provided withnuts at their outer ends. Of course, the T-head stud nuts must beloosened to enable the roll support to be slidably moved. The rollsupports 39 and 49 for the roll 16 are secured inthe same manner to thebed plate 2, which likewise is provided with guideways having a T-shapeslot, as indicated at 65 in FIG. 4. Of course, the roll supports may besecured in any other well-known manner than that described.

The axes of the rolls 12 to 16, inclusive, are in parallel horizontalplanes, as may be best observed from FIG. 6, the rolls 12 to 16,inclusive, of the cage of rolls are equally distant from -the axis ofany diameter pipe being formed. The bearing shafts 22 to 26, inclusive,respectively at the front ends of the rolls 12 to 16, inclusive, and thebearing shafts 27 to 3d, inclusive, at the rear ends of the rolls 12| to16, inclusive, are provided with key slots adaptable for slidingengagement with iixed keys to prevent rotational movement of the shafts22-31, inclusive, in their respective glide bearings.

Each of the shafts 22-31, inclusive, is moved inwardly or outwardly by ajack screw of a well-known worm and worm gear type, rigidly mounted inthe respective Each of the Worm gears of the jack screws is providedwith an internal screw-threaded axial bore which is in engagement with ascrew thread formed on a portion remote from the bearing end of therespective shafts 22-31 mounted therein. The worm shafts of each of thejack screws for the shafts 22-31, inclusive, are all interconnected inthe wellknown mechanical manner by means of miter gears, shafts, splineshafts, etc. to a common drive shaft connected by clutch means to amotor-driven worm gear speed reducer, or the like. In the apparatusshown herein, said common drive shaft is connected selectively by clutchmeans to the motor-driven means which is used to effect horizontalmovement of the roll support members.

With the drive shafts of the worms of all jack screws interconnected toa common drive shaft, all of the bearing shafts 22-31, inclusive, aremoved simultaneously to effect simultaneous and concentric inward oroutward movement of the rolls 12 to 16, inclusive, comprising the cageof rolls for helically winding the strip into a series of relatedconvolutions.

Accordingly, when it is desired to form pipe of any diameter within thecapacity of the apparatus, the center roll, or mandrel roll, is rstmoved out of position, if neccssary, in the manner hereinafterdescribed, and the rolls 12 to 16, inclusive, are moved simultaneouslyand concentrically, either inwardly or outwardly, as desired, until in aposition where the effective diameter of the cage of rolls is that ofthe desired outside diameter of the pipe to be formed.

It is to be particularly noted that my invention is not limited toapparatus which embodies a cage of 5 rolls as indicated in FIGS. 2 to 6,inclusive, as the cage of rolls may be formed of a greater number ofrolls. Moreover, in FIG. 1, which was made from a photograph of anapparatus embodying my invention made for producing spiral pipe for aspecic use, a small roll 15s is used in lieu of the roll 15 of theapparatus shown in FIGS. 2 to 6, inclusive.

If the spiral pipe forming apparatus as heretofore described is to beutilized only in the production of pipe of the same diameter and fromsubstantially the same width of steel strip, it would not be necessaryto have the rolls mounted on bearing shafts which are selectivelyaxially movable or the bearing shafts mounted in roll supports which areselectively slidably movable horizontally, as there would be nonecessity for effecting any change in the effective diameter of the cageof rolls or in the positioning of the rolls.

A center roll 75, or mandrel roll, is journalled at its rearward end intwo spaced-apart bearings, each of which s mounted on a shaft and jackscrew member, within its respective support member 76 and support member77, in a manner similar to that heretofore described with reference tothe rolls 12 to 16. The support members 76 and 77 are mounted on thebase member 2 in the same manner as heretofore described with referenceto the roll supports 39 and 49 for the roll 16. The support members 76and 77 may be moved simultaneously as a unit by means of the screwshafts 7 9-79 in the same manner as heretofore described with referenceto the roll supports 39 and 49 for the roll 16.

The axis of the mandrel roll 75 is parallel to the axes of the rolls 12to 16, inclusive. The two bearings for the mandrel roll 75 are adaptedto be moved simultaneously by their shafts and jack screw members in anangular plane indicated by the dash line M-M in FIG. 6, to effectrepositioning movement of the mandrel 75 necessitated by changes in theeffective diameter of the cage of rolls 12 to 16, inclusive, to producespiral pipe of different diameters. The dash line M-M in `FIG. 6indicating the angular plane of movement of the mandrel roll 7S is aline passing between the center of the cage of rolls and the median linebetween the axes of the bottom roll 16 and the lower rear roll 12, whichin FIG. 6 is a plane substantially 36 from the vertical.

'I'.he respective jack screw members for the two bearings at therearward end of the mandrel roll 75 are connected together forsimultaneous movement by the shaft 83 which is operatively connected bysuitable gearing to the shaft 84 on which is mounted the pulley 85. Thepulley 85 is connected by a belt to an electric motor, indicated at $6.

The means to effect simultaneous movement of elements, such as bearings,with the use of jack screw members operatively connected to suchelements forms no part of my present invention, as various means foreffecting the desired purpose are well known, and require only the useof designing skill utilizing well-known mechanical movements.Accordingly, I deem it not necessary to show fully and describe thespecific details of the jack screw members, etc. as such constructionsare old and well known in various arts.

As indicated in FIGS. 4, 6, and 8, the center roll, or mandrel roll, 75may be driven in a counterclockwise direction, as viewed in FIG. 6, byan adjustable speed motor 90 connected by the coupling 91 to a worm gearspeed lreducer 92. A sprocket 93 on the output shaft of the speedreducer 92 is connected by a sprocket chain 95 to a sprocket gear 96rigidly secured to the rear end of the mandrel roll 75 in any convenientmanner.

It is to be understood that although no driving means are shown for anyof the outer rolls 12 to 16, inclusive, the rolls 12 to 16, inclusive,could be driven, if desired, in the same manner as that indicated forthe mandrel roll 75. It is noted that in the production of spiral pipeof certain diameters and wall thicknesses, it may be found to be notnecessary to have even the center roll, or mandrel roll, as a drivenroll if the strip from which the spiral pipe is to be formed ispropelled into the cage of rolls with sufficient force to helically windthe strip into a series of related convolutions. n

Moreover, it is noted that in the production .of spiral pipe of certaindiameters and wall thicknesses, it may not be necessary to include acenter roll, or mandrel roll, and -that the strip of metal may behelically Wound into a series of related convolutions in the roll cageby the effective forces propelling the strip into the spiral pipeforming apparatus.

As stated heretofore, it may be found to be desirable to have thecenter, or mandrel roll, `and/or one or more of the outer rolls whichform the cage of rolls of a slatted construction in order to facilitatethe movement of convolutions of strip of certain diameters and wa-llthicknesses through the apparatus. Referring to FIGS. 7 to 1l,inclusive, which show Ya form of center, or mandrel, roll `of slattedform; the roll core 100 is a solid roll which is provided with an axialbore 1101 therethrough. The router portion of the roll is formed,conveniently, by a series lof eight segments, or slats, 102. As shown inFIG. l0, the front end of each segment 102 is bored to form a socket fora rod 4103 on which the segment 102 is slidably mounted. The socket isprovided, conveniently, with an oilite bushing to provide ease ofreciprocating movement of the segment 102 on the rod. The rod 103 isrigidly secured at its front end to a ring member 105 which is rigidlyfastened to the outer end of the core 100 by a series of bolts 106, asbest shown in FIGS. 9 and 10. The core 100 is provided with a series ofchannels 108 and each segment member 102 is provided with correspondingchannels 109 formed in the undersurface.

The channels 108 and 109 form guideways for a multiplicity of ballbearings 107 to minimize the friction of movement of the segments 102.The ball bearings 107 are confined laterally by pin means 110, asindicated in FIG. 11. I nd it convenient to interpose sealing strips 112of suitable material to prevent foreign matter, such as abrasive uxmaterial, from getting into the ball bearing guideways 108 and y109. Asindicated in FIG. 10, each segment 102 is connected by suitable means,such as pins 114, to a piston rod extension 116 of its air cylinder 117.

Each segment 102 of the roll 75 in its rotation is successivelyk engagedby the steel strip, as the steel strip is being helically wound in theroll cage, and the movement of the strip will cause a slat 102 when soengaged to be moved `on its rod 103 toward the front end of the roll. Asa segment 102 of the roll moves out of engaging contact with the stripbecause lof the rotation of the roll, the segment is freed from forwardmovement on its rod 103 and the segment is then restored to its initialposition at the rear end of the roll by means .of its air cylinder 117,the piston rod 116 of which is operatively connected to the segment.

As the air cylinders are carried by and rotate with the roll 75, it isnecessary that an air valve assembly be used to afford communication ofair to and release of air from each air cylinder. Such an air valveassembly is indicated in FIG. 11, wherein the air passageway 119 of thestationary air inlet and exhaust plate 120 is in cornrnunication withthe rotatable cylinder intake plate 121 provided with a series ofpassageways 122 which are connected by suitable piping means 125 to theair port 126 at the underside of Ithe piston 127 of each air cylinder117. The inlet plate 120 is maintained in fluidtight relation with thecylinder intake plate 121 by means of a series of compression springs129 having one end seated in sockets 130 in the spring holder plate 131.The opposite ends of said series of springs 129 bear against the thrustbearing 132. The intake plate 121, plate 120, thrust bearing 132, andspring holder plate 131 are maintained in position between positioningclamps 134 and 135 on the drive adaptor 136.

It is to be noted that if in spiral pipe forming apparatus embodying myinvention, the center roll, or mandrel roll, and/ or any or all of the.outer rolls be of what I have termed slatted roll construction, anysuch slatted roll may be converted readily to a solid roll form for alleffective purposes, eg. by merely moving all the segments, or slats, 102to their forwardmost position and inserting a series of blocks at therearward ends to thereby prevent any movement of the segments 102. Theblocking means may be held, conveniently, lby an encircling band. Ofcourse, the air cylinders 117 also would be made inoperative.

It is noted that unless it be contemplated that my improved apparatusmight be -used for the producing of spiral pipe of a `diameter and wallthickness which may make it more desirable to use slatted rolls, allrolls usually would be of the solid roll type. It is obvious that aslatted form of roll is far more costly to manufacture than a solid typeroll.

Referring to FIGS. 1 and 2, a coil of steel strip 1140 is mounted withfreedom of rotation in a coil cradle of the well-known construction (notshown) at the rear, or entrance end, of the uncoiler and straighteningmachine, or roller leveler, 141. The coil cradle, and uncoiler androller leveler, may be of any of the well-known types lit-ted for thepurpose which are .available on the market, and form no part of myinvention. The steel strip as uncoiied from the coil 140 passes througha series `of powerdriven rolls 142 indicated diagrammatically in FIG. 5.The strip is forcibly propelled from the roller leveler through opposedsteel plates 143 and 143 spaced apart only the distance required by thethickness of the strip to the table on which it is carried over an entryroll 145. The entry roll 145 is journalled at its front end in labearing 145a formed at the upper end of the shaft 146. The roll 145 isjournalled at its rear end in a bearing 145b formed at the upper end ofthe shaft 147. The bearing shaft 146 is slidably key mounted in a -guidebearing in the roll support member 39, and the bearing shaft 147 isslidably key mounted in a guide bearing in the roll support member 49.

The entry roll 14S is adapted to be moved vertically upwardly ordownwardly by connected gear means in engagement with the screw-threadedlower portions of the shafts 146 and 147. The tops of the two rolls 145and 16 are maintained in the same plane. The propelled straightenedstrip 140 moves from the table 144 to the rolls 1'45 and 16 in a planetangential to the top of the rolls.

The entrance angle at which the steel strip enters the forming apparatusto be formed helically into a series of related convolutions dependsupon the width of the strip and the diameter of the pipe to be produced.Accordingly, the frame support 150 for the roller leveler 141 ispivotally movable labout a pivot member 151 rigidly fixed to the bedplate, br base, 2 of the forming and welding apparatus. The `framesupport 150 is provided with roller means 153 which engage arcuatetracks 154- to facilitate movement of the uncoiler and roller leveler toeffect a change in the entrance angle of the steel strip to the cage ofrolls. As the forming and Welding apparatus is capable of producingspiral pipe of varying diameters, it is necessary to raise and lower theuncoiler, roller leveler, `and table 144 so that the strip may betangential to the tops of the changed positions of the rolls 145 and 16.Such raising or lowering of the roller leveler, etc. may be effected byany convenient means.

In FIG. 1, I have indicated somewhat .diagrammatically raising andlowering means consisting of a series of jack screws 156, convenientlymounted at the `four corners of the frame support 156. The channelmembers 157 on which the roller leveler is mounted are rigidly connectedto the top surface pads of the `shafts of :the jack screws. The seriesof jack screws are connected together in the well-known manner bysuitable shafts and gearing so that al1 jack screws may be raised orlowered simultaneously. Movement of the jack screws is effectedmechanically by an electric motor and worm gear speed reducer, or thelike, operatively connected to the means for effecting simultaneousmovement of :the jacks.

The support 161 for the forward end of the table 144, correspondingly,is adjustable in `accordance with the changes in height of the rollerleveler.

Although I have described herein the effecting of a change in entranceangle at which the strip enters the forming -apparatus by moving thecoil 'of strip, roller leveler, etc. about a pivot point on the bedplate 2 of the forming apparatus, it is obvious that the roller leveler,etc. could be maintained in xed position and the forming and weldingapparatus made pivotally movable with respect to a stationary rollerleveler, etc. Correspondingly, the forming and welding apparatus couldbe mounted on jack screws, or the like, and the forming and weldingapparatus raised or lowered in setting for production of pipe of varyingdiameters so that strip forcibly propelled at a fixed level from theroller leveler, etc. would enter the forming and welding apparatustangential to the top of the entry and bottom rolls thereof.

The strip passes from the entry roll 145 to the top of the bottom roll16, then beneath the center roll, or mandrel roll, 7S and thereafter tothe rolls 12, 13, 14, and 15. The edges of the `abutting convolutionsare welded at the point indicated by X, which is at a point slightlyless than 180 of the entering convolution, and where the forward edge4of the entering convolution is Welded to the rearward edge `of theprecedin-g convolution, said edges being in abutting relationship atthis point. lOf course, the point of weld could be at any point afterthe aforesaid weld point of slightly less than 180.

The abutting edges of the convolutions may be welded 'by any lof thewell-known welding means, such as submerged arc welding, resistanceWelding, high frequency welding, gas Welding, etc. In FIG. l I haveindicated submerged arc welding means, including 'a diagrammaticrepresentation of any of the well-known welding heads which is adaptedto feed weld-ing wire 171 from the supply coil 172. A welding ux supplyhopper 174 is connected the well-known manner by `a conduit 175 tofurnish ux at the point of weld.

As heretofore stated, the center roll, or mandrel roll, is provided withan axial 'bore 101 completely therethrough. A rigid pipe 175., extendingat each end beyond the mandrel length, is provided at its front end witha bracket and supporting means 176 on which is mounted a small aircylinder 177 carrying va welding back-up shoe 178 which is positioned inthe well-known manner at the weld point. If the welding back-up shoe iswater-cooled, the water conduit connections thereto are also carriedthrough the bore 101 in addition to the air `conduit for supplying airto the air cylinder 177 utilized to maintain the welding shoe 178 incontact with the inner surface ot the steel strip at the point of weld.

If desired, the abutting edges of the helically wound convolutions ofstrip as heretofore described may be welded 4internally by welding meanssupported on the forward end of the pipe 175, which extends through andbeyond the axial bore 101 of the center roll, or mandrel roll, 75; or,if desired, the helically Wound convolutions of strip may be welded bothexternally and internally in the manner described.

The base, or bed plate, 2 of the forming and welding apparatus may beextended at its rearward end so that the mandrel roll `and its supportsmay be retracted as a separate unit to a position rearward `of theforming and welding apparatus per se, so that the forward end of themandrel roll and the forward end of the pipe 175 supporting the weldingback-upy shoe tand/o1' the internal welding means will be in the open.It difficulties occur at the welding back-up shoe Zone in apparatus inwhich the mandrel roll is not retractable, it is necessary to cut out asection cf pipe around this back-up `shoe area and make the necessaryrepairs or replacements by working through such opening which is at amost inconvenient location for working.

I find it desirable to support the finished spiral pipe 180 as itemerges from the forming and welding apparatus by lmeans of anadjustable support 181 of any of the wellknown types, such as thatindicated in FIG. 1.

Operation The apparatus as vshown herein was designed for the productionof spiral pipe within a diameter range of 14 in. to 24 in. from steelstrip with a possible maximum thickness of .250 in.

The rolls 12 to 16 of the cage of rolls vare moved simultaneously andconcentrically in the manner heretofore described so that the effectivediameter of the cage of rolls is the outside diameter of the spiral pipeto be produced. The positioning of the rolls to the proper eective cagediameter may be done facilely by using a templet ring or rings whichhave the same diameter IaS that of the pipe to be produced. The entryroll 145 is correspondingly moved so that the top of the roll 1-45 is inthe same plane as the top ofthe bottom roll 16 of the cage of rolls.

ln the production of spiral pipe of a given outside diameter from steelstrip, it is desirable to use the Width of strip which will produce themost pipe w-ith the least .amount of welding. The entrance angle, orfeed angle, of the strip varies with .the width of the strip. Forexample, in the production of 16" O.D. spiral pipe from 32" width strip,the entr-ance or feed angle lwith respect to the 4axes of the rolls 16,12, etc. ofthe cage of rolls is 50 28 or 50.5 degrees; :and in theproduction of 16" OD. spiral pipe from 40" width strip', the entrance orfeed angle is 37 16".

The roller leveler 141,V with the coil of strip 140, platen table 144,etc. is properly moved about the pivot 151 in the manner heretoforedescribed so that the straightened strip 140 will be moved at themathematically determined en-trance angle for the Width of strip beingused.

The roller leveler 141, with the coil of strip 140', platen table 144,etc. is `then raised or lowered inthe manner heretofore described sothat the strip 140` will be moved in a plane to the top of the rolls 145and 16. The support 161 at the forward end of the table 144 iscorrespondingly adjusted in accordance with the changes made in thetable 144, etc.

I-f required, the ro-lls 12 to 16 and 145 may be moved horizontally inthe manner heretofore described by movement as a unit of the rollsupport members Iat the forward and rear ends of any roll required to berepositioned.

The strip 140 is uncoiled by the uncoiler in the wellknown manner and,as indicated in FIG. 5, passes between the irst opposed pair ofpower-driven pusher rolls of the roller leveler 141, thence through theleveler rolls, indicated diagrammatically by the Ilive smaller diameterrolls, and thence between the second opposed pair of power-driven pusherrolls. The strip is forcibly propelled between the opposed steel plates143 and 143', or platen members, in =a plane to the top of the entryroll 145 and the bottom roll 16. If required, guide rollers or guideshoes may be utilized to maintain the longitudinal movement of the stripat the set entrance angle.

The strip moves from the roll 16 beneath the properly positioned center1or mandrel roll 75 to the roll 12. The mandrel roll is positioned inthe manner heretofore described so that an initial curvature of agreater radius than the radius of the pipe to be formed is imparted tothe longitudinally moving lstrip 140 diagonally of its longitudinalaxis.

The strip 140 is helically Wound in the cage of rolls into convolutionsto form a pipe of an outside diameter which is the effective diameter ofthe cage of rolls. As the initial curvature imparted to the strip is ofa greater radius than the radius of the pipe to be formed, rand as such4initially curved strip is helically wound into convolutions whileconfined by therolls of the roll cage to a radius of curvature which isless than the initial r-adius of curvature imparted to the strip,roundness and mainftenance of the `desired diameter of the resultantpipe is assured. As indicated in FIG. 3, an edge guide roll, lor rolls,180 is positioned approximately at the point where the rear edge of thestrip 140 has made an initial one half of a convolution to assure themaintenance of the strip in proper location.

It is important to note in my method and apparatus that the multiplicityof rolls of the roll cage exent resistance `to the longitudinal movementof the curved strip which is sufficient to cause abutment of theIforward edge of the convolution being formed with the rear edge of thenext preceding fully formed convolution. However, the

l@ rolls of the roll cage exert no circumferential resistance to themovement of the curled Strip in the cage of rolls as would tend tounwind or open the seam It is noted that in the prior art methods of andapparatus for forming spiral pipe, those skilled -in the endeavored tohave all forming means as near frictionless as possible.

The abutting edges of the convolutions are welded t0- gether,conveniently, at a point slightly in advance of the point where thefront edge of the convolution being formed has made a half turn, asindicated at 171 in FIG. 6, and at X in FIG. 2.

As indicated in FIG. 1, said abutting edges are continuously weldedtogether by submerged :arc welding with use of a welding head k of thewell-known type, electrode wire 172, and llux supplie-d at the point ofweld in the well-known manner by the flux conduit connected to thewelding flux supply hopper 174.

Aldiough I have referred to outside submerged arc welding, it is obviousthat the abutting edges of the convolutions can be welded on the inside,and that said abutting edges can be welded by a combination of outsideand inside welding.

It also is important to note that the initial imparting of la curvatureof greater radius to the strip than the radius of the pipe to be formedand the winding of such initial curved strip helically into convolutionsWhile conlined in a ro'll cage of a radius less then the initial radiuseffect-s a cold working of the metal strip to `a certain degree, and nospecial devices are required to maintain the edges even in -an up anddown direction. Any commercially allowable camber of 1A in. in 8 ft. oflength in the strip is absorbed, or distributed to a non-effectivedegree in advance of welding.

I do not desire to limit myself to the apparatus and method of operationas specically described lherein, as it is obvious that variousmodifications may be made therein without departing from the essentialfeatures of my invent-ion.

I claim:

1. The method of forming metal tube from a helically wound elongatedsteel ,strip comprising the steps of imparting to a longitudinallymoving steel strip diagonally of its longitudinal axis an initialcurvature of a slightly greater radius than the radius of the tube to beformed; forming said curved strip helically into convolutions to form atube while confining said strip to a radius of curvature which is.slightly less than the initial radius of curvature imparted to saidstrip, which inherently changes the steel to its so-called plasticstate, said tube being moved longitudinally of its axis by the `forcesof said moving strip; applying resistance to the longitudinal movementof said curved strip suiicient to cause abutment of the edges in theplastic state of said convolutions of the tube; and continuously weldingtogether the abutting edges.

2. The method of forming a helically wound metal tube from an elongatedsteel strip comprising the steps of imparting to a propelledlongitudinally moving steel strip diagonally of its longitudinal axis aninitial curvature of a radius slightly greater than that of the tube tobe formed; rforming said curved strip helically into convolutions toform a tube While conning said strip to a radius of curvature which isslightly less than the initial radius of curvature imparted to saidstrip, which inherently changes the steel to its so-called plasticstate, said tube being moved longitudinally of its axis by the forces ofsaid propelled moving strip; applying resistance to the longitudinalmovement of said curved strip suflicient to cause abutment of the edgesin plastic state of said convolutions of the tube; and continuouslywelding together the abutting edges.

3. The method lof forming a helically Wound metal tube Ifrom anelongated steel strip comprising the steps of imparting to alongitudinally moving steel strip diagonally of its longitudinal axis,lan initial curvature of a slightly Igreater radius than the radius ofthe tube to be formed; forming said curved strip helically intoconvolutions to form a tube while conning the strip to a radius ofcurvature which is slightly less than the initial radius of curvatureimparted to said strip, which inherently changes the steel to its`so-called plastic state, said tube being moved longitudinally of itsaxis by the force of said propelled moving strip; applying resistance tothe longitudinal movement of said curved strip suflicient to causeabutment of the forward edge in plastic state of the convolution being`formed with the rear edge `of the next preceding fully formedconvolution; and continousl-y Welding together the abutting edges at apoint where the convolution being formed is less than one-half aconvolution.

4. The method of forming a helically Wound metal pipe from an elongatedsteel strip comprising the steps of roll forming a propelledlongitudinally moving steel strip diagonally of its longitudinal axis toan initial curvature of a slightly greater radius than the radius of thepipe to be formed; forming said curved strip helically into convolutionsto form a pipe while confining said strip to a radius of curvature whichis slightly less than the initial radius of curvature imparted to thestrip, which inherently changes the steel to its so-called plasticstate, said pipe being moved longitudinally of its axis by the forces ofsaid propelled moving strip; applying resistance to the longitudinalmovement of said curved strip suflicient to cause abutment of theforward edge in plastic state of the convolution being formed with therear edge of the next preceding fully formed convolution; landcontinuously welding together said abutting edges.

References Cited in the le of this patent UNITED STATES PATENTS 367,494Alden Aug. 2, 1877 1,739,757 Hand Dec. 17, 1929 1,875,560 Cammer Sept.6, 1932 1,884,658 Gladkov Oct. 25, 1932 2,549,032 Taylor Apr. 17, 19512,635,572. Hester'man Apr. 21, 1953 2,693,779 Padgett Nov. 9, 1954FOREIGN PATENTS 754,020 Great Britain Aug. 1, 1956

1. THE METHOD OF FORMING METAL TUBE FROM A HELICALLY WOUND ELONGATEDSTEEL STRIP COMPRISING THE STEPS OF IMPARTING TO A LONGITUDINALLY MOVINGSTEEL STRIP DIAGONALLY OF ITS LONGITUDINAL AXIS AN INITIAL CURVATURE OFA SLIGHTLY GREATER RADIUS THAN THE RADIUS OF THE TUBE TO BE FORMED;FORMING SIAD CURVED STRIP HELICALLY INTO CONVOLUTIONS TO FORM A TUBEWHILE CONFINING SAID STRIP TO A RADIUS OF CURVATURE WHICH IS SLIGHTLYLESS THAN THE INITIAL RADIUS OF CURVATURE IMPARTED TO SAID STRIP, WHICHINHERENTLY CHANGES THE STEEL TOITS SO-CALLED PLASTIC STATE, SAID TUBEBEING MOVED LONGITUDINALLY OF ITS AXIS BY THE FORCE OF SAID MOVINGSTRIP; APPLYING RESISTANCE TO THE LONGITUDINAL MOVEMENT OF SAID CURVEDSTRIP SUFFICIENT TO CAUSE ABUTMENT OF THE EDGES IN THE PLASTIC STATE OFSAID CONVOLUTIONS OF THE TUBE; AND CONTINUOUSLY WELDING TOGETHER THEABUTTING EDGES.